README.md in cri-2.15.3 vs README.md in cri-2.15.4

@@ -10,10 +10,10 @@
 Cri is a library for building easy-to-use command-line tools with support for
 nested commands.
 
 ## Requirements
 
-Cri requires Ruby 2.3 or newer.
+Cri requires Ruby 2.4 or newer.
 
 ## Usage
 
 The central concept in Cri is the _command_, which has option definitions as
 well as code for actually executing itself. In Cri, the command-line tool